1. Field of the Invention
The present invention relates to an industrial robot utilizing a parallel link mechanism.
2. Discussion of the Prior Art
In an industrial robot of the above-mentioned type, a first arm and a first link are supported on the shoulder portion for swing movements about a common axis, while a mid portion of a second arm is pivoted at the upper end of the first arm for swing movement about a swing axis parallel to the common axis. Also, a second link parallel to the first arm is connected between the first link and the rear end of the second arm, thereby forming a parallel link mechanism together with the first arm, a rear portion of the second arm and the first link. Further, first and second motors for swinging the first arm and the first link, respectively, are mounted on the shoulder portion. The second arm is moved by a swing movement of the first link through the second link to be swung about the swing axis.
In such industrial robot, a wrist portion is attached to the front end portion of the second arm opposite to the rear end portion thereof, to which the upper end of the second link is connected. Therefore, the wrist portion cannot be moved far above the upper end of the first arm, thereby limiting the working area of the robot within an area in front of the first arm. Accordingly, such industrial robot can be used only in applications in which robots are placed on floors of plants (hereinafter referred to as floor installation applications). It cannot be used in applications in which robots are hung down from ceilings of plants (hereinafter referred to as ceiling installation applications). In the past, therefore, it is required to manufacture special industrial robots having a configuration suitable for the ceiling installation applications, if robots are required to be hung down from ceilings.